No abstract

Late blight caused by Phytophthora infestans is the most serious disease of potato worldwide. To understand the P. infestans population structure in northern Shaanxi, an emerging potato production region in China, 125 single‐lesion isolates were randomly collected from farmers' fields in 2009 and characterized phenotypically and genotypically. A mating type assay showed that 94 isolates were A1 mating type. Virulence determination of selected isolates on a set of differential potato lines containing R1 to R11, respectively, showed the presence of two pathotypes, of which the pathotype lacking avirulence genes Avr3, Avr4 and Avr10 was dominant. Isolates lacking all avirulence factors Avr1 to Avr11 were detected but at lower frequency (13·6%). Analysis for mtDNA haplotype showed all 61 examined isolates were IIa. A total of seven multilocus genotypes were distinguished among 125 isolates, as determined with seven polymorphic microsatellite markers. The genotype SG‐1 was dominant in the population with a frequency of 75·2% and was present throughout the region. Analysis of the phenotypic and genotypic structures of P. infestans populations indicated strict clonal reproduction of the pathogen and suggested that sexual reproduction probably does not occur. Potential implications for disease management are discussed.

Xerophytic stomatal traits may help plants maintain photosynthetic rates under water deficit; however, such adaptations are not well understood. A pot experiment was conducted with two winter wheat cultivars (Pubing 143, Zhengyin 1) during the grain-filling period. Net photosynthetic rate (P N ) and chlorophyll (Chl) content were significantly less affected by water deficit in Pubing 143 than that in Zhengyin 1, and the variation in both P N and Chl content were more stable in spikes compared to flag leaves. At 18 days after anthesis, stomatal conductance of spikes in Pubing 143 were 28% lower than that of the control, while transpiration rate was 34% lower in Zhengyin 1 under water deficit. We provided the first evidence of amphistomatous stomata on the lemma of winter wheat spikes through scanning electron microscopic observations. The finding of the amphistomatous stomata is an important contribution to stomatal distribution and may help explain how wheat spikes can maintain high photosynthetic rates even under drought conditions.

The peroxisome proliferator-activated receptor gamma coactivator-1 alpha protein, encoded by the PPARGC1A gene, plays an important role in energy homeostasis. The genetic variations within the PPARGC1A gene promoter region were scanned in 808 Chinese native bovines belonging to three cattle breeds and yaks. A total of 6 SNPs and one 4 bp insertion variation in the promoter region of the bovine PPARGC1A gene were identified: SNP -259 T>A, -301_-298insCTTT, -915 A>G, -1175 T>G, -1590 C>T, -1665 C>T and -1690 G>A, which are in the binding sites of some important transcription factors: sex-determining region Y (SRY), myeloid-specific zinc finger-1 (MZF-1) and octamer factor 1(Oct-1). It is expected that these polymorphisms may regulate PPARGC1A gene transcription and might have consequences at a regulatory level.

Abstract. Nuclear receptor-interacting protein 1 (NRIP1) specifically interacts with the hormone-dependent activation domain AF2 of nuclear receptors to inhibit transcription. Previous work has demonstrated this protein to be a key regulator in modulating transcriptional activity of many transcription factors, some of which are closely related to development and growth. In this study, we have successfully genotyped two newly identified bovine NRIP1 single-nucleotide polymorphisms (SNPs) (c.605A>G and c.1301G>A) using the T-ARMS-PCR method and validated the accuracy by means of PCR-RFLP assay using 1809 individuals of 9 different cattle breeds. The association analyses results indicated that c.605A>G locus was significantly associated with body weight and average daily gain in Nanyang cattle at 18 months (P < 0.05). Thus it can be inferred that T-ARMS-PCR is a rapid, reliable, and cheap method for SNP genotyping and that c.605A>G polymorphism in bovine NRIP1 is associated with growth traits. These findings will be of benefit for the application of DNA markers related to growth traits in marker-assisted selection (MAS), and will improve the promotion of beef cattle.